Public venues, for example, airports, can be very large. Passengers of various flights may walk through several terminals, or look around to shop or eat before or after a flight. In some instances, it is desirable to be able to track the location of various individuals in a large venue. Typically, to let a passenger know that the plane door is closing, an announcement is typically made over a loudspeaker throughout the airport. This is inefficient as no whereabouts of the passenger is conveyed in response. Some people do not pay attention to the loud speaker, or fail to hear their name, making the announcement inadequate. There exists a need for better systems of delivering messages to people in large venues.